> If Alan is reading this, I'm wondering if I missed where that
> 'strategically placed diode' is located?
One way to do it is just to put a pair of back-to-back diodes in
parallel with the inputs. That protects against over-voltage of either
polarity.
One thing I always like to do when
Richard,
After a big search through my old documentation I have found all my design
notes on the power supplies I built, I still have the Fairchild voltage
regulator application handbook that I consulted at the time. Like you, I needed
to build this supply for my first solid state high power
Hello David, (and Alan), and thanks to John for the link showing the
added parts.
David, your PS sounds very similar to the one I built, also in the
70's. Mine has four 3055's on very large heat sinks that are overkill,
but I didn't know what to expect. It was at a time when we were going
I have a couple of homebuilt DC regulated supplies that I built a great many
years ago, the first is a simple 3A 13.5V one that was the very first supply I
ever built and it used a 723 with a single 2N3055 series pass transistor. I
remember I bought a lovely oil filled mains transformer for it,
The 723 regulator has some known reliability issues, but with proper
design they can be mitigated. In particular the differential voltage on
the error amplifier inputs is only rated for 5v. If one input is
connected to the 7.15V reference, then if the power supply output is
shorted the
Hi All,
Here is a link to a schematic for the 3/4 A power supplies with the
added parts for external voltage protection:
http://www.ameradio.com/doc/Astron%20RS-3A,%20RS-4A%20schematic.pdf
John KN5L
On 07/21/2016 07:41 AM, Myron Schaffer wrote:
> It used to be that waythe RS linear models
I was glad that I caught Jim's remark about blowing the 723 by being
connected to a battery with the PS off. And also Myron's answer.
Back in the tube TV days, I purchased a bare circuit board at Radio
Shack, (I think). The board was similar to an Astron circuit board, but
simpler. I
I blew up the LM-723 in my old Astron VS-35M by trying to use it as
a battery charger quite a few years ago (I bought the Astron to power
my TS-180S in 1981). A year ago it failed to output and blew the
fuses. Turned out one of the rectifiers shorted. I replaced both
and its working fine
Thanks Myron... Haven't cracked the case yet, but will check and verify...
__
Clay Autery, KY5G
MONTAC Enterprises
(318) 518-1389
On 7/21/2016 7:41 AM, Myron Schaffer wrote:
> Jim and Clay,
>
> It used to be that waythe RS linear models could not tolerate external
>
: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Myron
Schaffer
Sent: Thursday, July 21, 2016 8:42 AM
To: j...@audiosystemsgroup.com
Cc: elecraft@mailman.qth.net
Subject: Re: [Elecraft] Linear PS Recommendations
Jim and Clay,
It used to be that waythe RS linear models could
Jim and Clay,
It used to be that waythe RS linear models could not tolerate external
voltage present when unpowered, not anymore. Astron has incorporated
back-voltage protection through incorporation of some diodes installed in key
locations to prevent this.
You can verify if your supply
That would have been my recommendation. I discovered a couple of weeks ago that
I had a new-in-box RS-35M in my storage shed that I bought for a spare 20+ years
ago. Never needed it. Fired it up just for the heck of it and it's FB.
On 7/21/2016 2:24 AM, Clay Autery wrote:
Thanks Jim!
Yes,
Thanks Jim!
Yes, eventually there will be quite a collection of gear. My #1 Elmer
showed up at my door and surprised me with a NICE RS-35M to get me off
that SMPS. It is super quiet.
I haven't opened it up yet, but I know (from one of your papers) what to
look for. And I suspect my Elmer has
On Wed,7/20/2016 10:52 PM, Bob Nielsen wrote:
you probably don't need much more than 20 amp capability. I have used
an Astron RS-20 for the past 35 years but I would probably go for the
RS-35 or RS-50 if I was getting another one.
That depends on what gear other than the radio that you want
Since the KPA500 has its own linear supply, you probably don't need much
more than 20 amp capability. I have used an Astron RS-20 for the past 35
years but I would probably go for the RS-35 or RS-50 if I was getting
another one.
73, Bob N7XY
On 7/20/16 5:57 PM, Clay Autery wrote:
I am
I am looking for recommendations for a linear power supply to power my shack.
Right this minute I need one just for my K3s and P3, but at some point will be
adding a KPA500, KAT500, dual monitors, etc. Also, looking at building a dummy
battery to run my laptop off the shack supply (11.1VDC, so
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